This invention relates to a method and apparatus for use in the three dimensional location of the points on an object surface and, in particular, to a method and apparatus which utilize data developed from projected and reflected electromagnetic radiation.
In one type of the above apparatus, the electromagnetic radiation used is optical radiation or light and the apparatus employs well known optical triangulation techniques to determine the spatial locations of the object surface points from the data derived from the projected and reflected optical radiation. In this apparatus, structured light, (i.e., light with a well defined and well known shape), is projected onto the object surface. The reflection of this light from the surface is then collected along a known angle to the projected light yielding three dimensional coordinate data of the object surface.
In one form of typical arrangement, a projected plane of light is used and where the plane of light intersects the object it forms a line of light on the object surface. A camera, located at a fixed angle from the light plane, views the reflection (i.e., collects the reflected light) and provides data from which the coordinates of each point on the line, relative to the projector/camera sensor, can be computed. Another typical arrangement uses a projected pencil beam of light and the intersection of this beam with the object surface results in a spot. This spot on the object surface is viewed by a camera which provides data for computing the precise location of the spot relative to the projector/camera sensor. By scanning the sensor relative to the object, all the object surface point locations can be determined.
In many applications, it is desirable to develop sensor data or view a particular object from different angles. The motives vary but include the desire to remedy specular reflection or to avoid obscuration. This can be accomplished by moving a single sensor or by providing multiple sensors. In either case, if the positions of the sensors are random, considerable data merging arithmetic and processing is needed in order to render this information useful for object surface description. Furthermore, inaccuracies in the sensor placement mechanism or the position encoders yields data "seams" which are highly detrimental in applications demanding high surface mapping accuracy.
It is, therefore, an object of the present invention to provide an apparatus and method for use in object surface determination in which the requirements of data merging in a multi-sensor environment are reduced.